/*
 *                               POK header
 *
 * The following file is a part of the POK project. Any modification should
 * be made according to the POK licence. You CANNOT use this file or a part
 * of a file for your own project.
 *
 * For more information on the POK licence, please see our LICENCE FILE
 *
 * Please follow the coding guidelines described in doc/CODING_GUIDELINES
 *
 *                                      Copyright (c) 2007-2021 POK team
 */

/* e_atanhf.c -- float version of e_atanh.c.
 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
 */

/*
 * ====================================================
 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
 *
 * Developed at SunPro, a Sun Microsystems, Inc. business.
 * Permission to use, copy, modify, and distribute this
 * software is freely granted, provided that this notice
 * is preserved.
 * ====================================================
 */

#ifdef POK_NEEDS_LIBMATH
#include "math_private.h"
#include <libm.h>

static const float one = 1.0, huge = 1e30;

static const float zero = 0.0;

float __ieee754_atanhf(float x) {
  float t;
  int32_t hx, ix;
  GET_FLOAT_WORD(hx, x);
  ix = hx & 0x7fffffff;
  if (ix > 0x3f800000) /* |x|>1 */
    return (x - x) / (x - x);
  if (ix == 0x3f800000)
    return x / zero;
  if (ix < 0x31800000 && (huge + x) > zero)
    return x; /* x<2**-28 */
  SET_FLOAT_WORD(x, ix);
  if (ix < 0x3f000000) { /* x < 0.5 */
    t = x + x;
    t = (float)0.5 * log1pf(t + t * x / (one - x));
  } else
    t = (float)0.5 * log1pf((x + x) / (one - x));
  if (hx >= 0)
    return t;
  else
    return -t;
}
#endif
